U.S. patent number 9,910,003 [Application Number 14/885,220] was granted by the patent office on 2018-03-06 for methods and apparatus for a moisture detector.
This patent grant is currently assigned to Helvetia Wireless, LLC. The grantee listed for this patent is Helvetia Wireless LLC. Invention is credited to Roc Lastinger, Brian C. Woodbury.
United States Patent |
9,910,003 |
Lastinger , et al. |
March 6, 2018 |
Methods and apparatus for a moisture detector
Abstract
A system for detecting the presence of a liquid. The system
includes a sensor, a cap, and a reader. The sensor includes at
least three conductors, a substrate, and a cover. The conductors
are positioned between the substrate and the cover. The cover
includes a first portion at a first position and a second portion
at a second position. The first portion and the second portion are
adapted for separation from proximate portions of the cover and
from the substrate to expose the conductors. The cap and the reader
are adapted for positioning against the substrate at the first
position and the second position respectively after separation of
the first portion or the second portion. Positioning the cap
against the against the substrate electrically couples two of the
at least three conductors to each other. Positioning the reader
against the substrate electrically couples the reader to the
conductors to detect the presence of the liquid.
Inventors: |
Lastinger; Roc (Cave Creek,
AZ), Woodbury; Brian C. (Gilbert, AZ) |
Applicant: |
Name |
City |
State |
Country |
Type |
Helvetia Wireless LLC |
Scottsdale |
AZ |
US |
|
|
Assignee: |
Helvetia Wireless, LLC
(Scottsdale, AZ)
|
Family
ID: |
61257234 |
Appl.
No.: |
14/885,220 |
Filed: |
October 16, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
62093805 |
Dec 18, 2014 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N
27/121 (20130101); G01N 27/06 (20130101); G01N
25/56 (20130101) |
Current International
Class: |
G01N
27/04 (20060101); G01N 27/06 (20060101); G01R
27/02 (20060101); G01N 27/12 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2312368 |
|
Apr 2000 |
|
CA |
|
558057 |
|
Sep 1993 |
|
EP |
|
563809 |
|
Oct 1993 |
|
EP |
|
1751302 |
|
Feb 2007 |
|
EP |
|
2218837 |
|
Nov 1989 |
|
GB |
|
1989000681 |
|
Jan 1989 |
|
WO |
|
2000000801 |
|
Jan 2000 |
|
WO |
|
2006086178 |
|
Aug 2006 |
|
WO |
|
2009018650 |
|
Feb 2009 |
|
WO |
|
2010064753 |
|
Jun 2010 |
|
WO |
|
Primary Examiner: Hollington; Jermele M
Assistant Examiner: Shah; Neel
Attorney, Agent or Firm: Letham Law Firm LLC Latham;
Lawrence
Claims
What is claimed is:
1. A system for detecting a presence of a liquid, the system
comprising: a sensor, the sensor including at least two conductors;
and a reader, the reader including a processing circuit; wherein:
prior to exposure of the sensor to the liquid, the processing
circuit: provides a current through a first conductor of the at
least two conductors; detects a voltage across the first conductor
to determine a magnitude of the impedance of the first conductor;
in accordance with the magnitude of the impedance, determines a
model of the sensor; and provides a notice regarding the model of
the sensor; and after exposure of the sensor to the liquid, the
reader detects the presence of the liquid.
2. The system of claim 1 wherein: the processing circuit further
detects a further electrical characteristic of the sensor; and the
processing circuit interprets the characteristics in light of the
model number.
3. The system of claim 1 wherein: the processing circuit comprises
a store of information; and the processing circuit further
determines the model of the sensor in accordance with the store of
information.
4. The system of claim 1 wherein the reader determines a location
of the liquid with respect to the sensor in accordance with the
magnitude of the impedance.
5. The system of claim 1 wherein the model correlates to
information regarding a physical layout of the sensor.
6. The system of claim 1 wherein prior to exposure of the sensor to
the liquid, the processing circuit further: provides a voltage
across the first conductor; and detects a current through the first
conductor to determine the magnitude of the impedance.
7. The system of claim 1 wherein the processing circuit stores the
magnitude of the impedance.
8. The system of claim 1 wherein, wherein the processing circuit
transmits the notice via a communications circuit.
9. The system of claim 1 wherein the processing circuit: includes a
look-up table; and accesses the look-up table to correlate the
magnitude of the impedance to the model of the sensor.
10. The system of claim 9 wherein: the reader further comprises a
communications circuit; and the processing circuit receives the
look-up table via the communications circuit.
11. A method for determining a model number of a sensor, the method
performed by a processing circuit, the sensor for detecting a
presence of a liquid, the method comprising: prior to exposing the
sensor to the liquid: providing a current through a conductor of
the sensor; while providing the current, measuring a voltage across
the conductor; determining in accordance with the current and the
voltage a magnitude of the impedance of the conductor; in
accordance with the magnitude of the impedance, determining the
model number of the sensor.
12. The method of claim 11 wherein determining comprises using a
look-up table to correlate the magnitude of the impedance to the
model number of the sensor.
13. The method of claim 11 wherein determining comprises: accessing
a store of information; using the store of information to correlate
the magnitude of the impedance to the model number of the
sensor.
14. The method of claim 11 wherein determining comprises: receiving
information via a communications circuit; using the information to
correlate the magnitude of the impedance to the model number of the
sensor.
15. The method of claim 11 further comprising transmitting a notice
via a communications circuit regarding the model number.
16. A method for determining a model number of a sensor, the method
performed by a processing circuit, the sensor for detecting a
presence of a liquid, the method comprising: prior to exposing the
sensor to the liquid: providing a voltage across a conductor of the
sensor; while providing the voltage, measuring a current through
the conductor; determining in accordance with the current and the
voltage a magnitude of the impedance of the conductor; in
accordance with the magnitude of the impedance, determining the
model number of the sensor.
17. The method of claim 16 wherein determining comprises using a
look-up table to correlate the magnitude of the impedance to the
model number of the sensor.
18. The method of claim 16 wherein determining comprises: receiving
information via a communications circuit; using the information to
correlate the magnitude of the impedance to the model number of the
sensor.
19. The method of claim 16 further comprising transmitting a notice
via a communications circuit regarding the model number.
Description
FIELD OF THE INVENTION
Embodiments of the present invention relate to moisture sensors and
processing circuits that cooperate with the moisture sensors to
detect the presence of moisture.
BRIEF DESCRIPTION OF THE DRAWING
Embodiments of the present invention will be described with
reference to the drawing, wherein like designations denote like
elements, and:
FIG. 1 is a functional diagram of a moisture detector according to
various aspects of the present invention;
FIG. 2 is a top plan view of an implementation of a moisture sensor
according to various aspects of the present invention;
FIG. 3 is a perspective plan view of the substrate and conductors
of FIG. 2;
FIG. 4 is the top plan view of FIG. 2 with liquid present and
indicators of electrical loops;
FIG. 5 is a cross section of the moisture sensor of FIG. 4 at
5-5;
FIG. 6 is a plan perspective view of a clip for coupling to a
moisture sensor according to various aspects of the present
invention;
FIG. 7 is a top plan view of another implementation of a moisture
sensor with liquid and electrical loops indicated;
FIG. 8 is a plan view of another implementation of a moisture
sensor positioned in a roll prior to deployment according to
various aspects of the present invention;
FIG. 9 is a plan view of the moisture sensor of FIG. 8 after
deployment;
FIG. 10 is a cross-sectional view of the moisture sensor of FIG. 9
at 10-10;
FIG. 11 is a plan view of the conductors of the moisture sensor of
FIG. 8;
FIG. 12 is a plan view of reader and a cap that couple to the
moisture sensor of FIG. 8;
FIG. 13 is a plan view of another implementation of a moisture
sensor according to various aspects of the present invention;
FIG. 14 is a plan view of an exposed area of the conductor of FIG.
13;
FIG. 15 is a plan view of caps for coupling to the conductors of an
exposed portion of the moisture sensor of FIGS. 13 and 14 for
coupling a reader;
FIG. 16 is a plan view of another implementation of a moisture
sensor according to various aspects of the present invention;
and
FIG. 17 is a plan view of a corner coupler for the moisture sensor
of FIG. 16.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A moisture detector may include a moisture sensor and a reader. A
moisture detector may detect the presence (e.g., existence,
occurrence) of moisture (e.g., liquid, salt water, urine, blood). A
moisture sensor may cooperate with a reader so that the reader may
detect the position and/or spread (e.g., extent, area) of a liquid
with respect to the moisture sensor, the conductors of the moisture
sensor and/or a substrate (e.g., pad, layer) on which (e.g., in,
under) the moisture sensor is positioned.
The physical structure of a moisture sensor may cooperate with the
physical structure of a reader so that the reader may removeably
couple to the moisture sensor. A moisture sensor may be integrated
into a substrate such that coupling a reader to the substrate
further couples the reader to the moisture sensor. A reader may be
removed from a substrate/moisture sensor so that it may be reused
by coupling it to a different substrate/moisture sensor. A reader
may detect when it is properly (e.g., electrically, mechanically)
coupled to a moisture sensor. A reader may detect an initial state
of a moisture sensor and/or substrate prior to the introduction of
moisture into the moisture sensor and/or substrate.
The substrate and moisture sensor may be formed of flexible
materials so that prior to deployment, the substrate and moisture
sensor may stowed (e.g., stored) in a compacted (e.g., rolled up,
folded) form. The substrate and/or moisture sensor, in whole or in
part, may be form of a rigid material such that the length prior to
deployment and after deployment is substantially the same. The
substrate and moisture sensor may be manufactured in standard
lengths for deployment. The substrate and moisture sensor may be
manufactured for deployment in variable lengths. Couplers may be
used to couple two or more lengths of substrate/moisture sensor.
Couplers may further be used to facilitate coupling a reader to a
substrate/moisture sensor.
For example, moisture detector 100 includes reader 120 and moisture
sensor 160. Moisture sensor 160 may be coupled to, positioned on,
and/or integrated into pad 170. Pad 170 may include one or more
layers of material. One or more layers of pad 170 may absorb or
repel moisture. Moisture sensor 160 may be coupled to, positioned
on, and/or integrated into one or more of the layers of pad 170.
One layer of pad 170 may be referred to as a substrate. Moisture
sensor 160 may be coupled to the substrate of pad 170. A substrate
may be formed of an absorbent or non-absorbent material. Moisture
sensor 160 or at least conductors 150 may be covered (e.g.,
positioned on, positioned over, positioned on top of) by an
absorbent layer (not shown in FIGS. 1-4). This absorbent layer may
be referred to as a cover. Pad 170 may include a non-absorbent base
layer. Pad 170 and conductors 150 may have any shape for a
particular application, for example, the shape of a diaper.
Moisture sensor 160 may be coupled to, positioned on, and/or
incorporate into a portion of pad 170 or most of the area of pad
170.
A cover may be formed of a material (e.g., dielectric) that when
dry does not conduct electricity. However, the liquid absorbed by a
cover may be conductive so that the liquid conducts a current.
A reader may detect the presence of a liquid in a moisture sensor
and/or the substrate. A reader may detect a position of a liquid
along a length of a conductor and thereby the position of the
liquid with respect to the moisture sensor. The area of a moisture
sensor may correlate to the area of a substrate, so determining the
position of a liquid with respect to the moisture sensor means that
the position of the liquid may be correlated to a location on the
substrate. A reader may detect an area of the spread of a liquid
with respect to the moisture sensor, so determining the spread of
the liquid may be correlated to an area of the liquid on the
substrate.
A reader may detect a current flow through a circuit and/or a
voltage across a circuit that includes some or all of a conductor,
a contact, the substrate, and/or the liquid positioned in the
substrate. A reader may electrically and mechanically couple to one
or more conductors of the moisture sensor or contacts thereof. A
reader may apply a voltage across one or more conductors. A reader
may detect a current flow through a conductor, a substrate, and/or
a liquid. A reader may detect an impedance (e.g., resistance) of a
conductor, a liquid, a substrate and/or a combination thereof.
A reader may determine a physical property of a conductor, a
substrate and/or a liquid. A physical property may include
capacitance, inductance, temperature, and impedance. For example, a
reader may determine a physical property of a liquid, a substrate,
a conductor, or a combination of the liquid and the substrate.
A reader, for example reader 120 of FIG. 1, may include contacts
130, processing circuit 122, communications ("comm") circuit 124,
power supply 126, and user interface 128.
A power supply may provide energy for operation of the reader. A
power supply may provide electrical energy for the operation of the
components (e.g., processing circuit 122, comm circuit 124, user
interface 128) of a reader. A power supply may provide electrical
energy for application to and/or across one or more conductors, the
substrate, and/or a liquid. A power supply may provide electrical
energy having known characteristics (e.g., voltage magnitude,
current magnitude, frequency, slew rate, pulse rate). A power
supply may convert electrical energy so as to change the
characteristics of the electrical energy provided. For example, a
power supply may convert electrical energy provided at a lower
voltage to electrical energy provided at a higher voltage. A power
supply may covert energy provided as a direct current into energy
provided as an alternating current. A power supply may include any
conventional power supply technology including battery
technology.
A processing circuit may electrically couple to one or more
conductors of a moisture sensor. A processing circuit may control
the provision of a current and/or voltage to a moisture sensor. A
processing circuit may detect a voltage across and/or a current
through a moisture sensor or a portion thereof. A processing
circuit may detect a current that flows through one or more
conductors of a moisture sensor, a substrate, and/or a liquid. A
processing circuit may detect a voltage applied across one or more
conductors of a moisture sensor, a substrate, and/or a liquid. A
processing circuit may record, store, manipulate, and/or report a
magnitude of a detected current and/or voltage. A processing
circuit may include any conventional circuit for providing,
controlling, converting, measuring, and/or detecting a voltage
and/or a current. A processing circuit may control a power supply
for providing a current and/or a voltage to the moisture
sensor.
A processing circuit may perform any conventional type of
calculation (e.g., add, subtract, multiply, divide, integrate,
compare) and/or conversion (e.g., AtoD, DtoA, scale, invert). A
processing circuit may store information. A processing circuit may
detect, measure, and/or report physical properties (e.g.,
temperature, voltage, current, time, slew rate). A processing
circuit may perform a calculation using detected, measured,
previously calculated, and/or stored information. A processing
circuit may receive information from a source outside of a reader
(e.g., user, database, moisture sensor manufacturer) and use such
information in any calculation and/or operation. A processing
circuit may receive information from a source outside of the reader
via a comm circuit. A processing circuit may report (e.g., provide)
a result of detecting, calculating, and/or converting. A processing
circuit may provide a result to a source outside the reader via a
comm circuit. A processing circuit may perform a function in
accordance with a result of calculating, converting, measuring,
and/or detecting.
A processing circuit may include any conventional circuit for
performing the functions of a processing circuit including
converters, sensors, microprocessors, signal processors, relays, op
amps, and comparators. A processing circuit may execute a stored
program to perform the functions of the processing circuit. The
execution of a stored program by a processing circuit may perform
the functions of a reader.
A comm circuit may communicate (e.g., transmit, send, receive)
electronically. A comm circuit may send information (e.g., data)
and/or receive information electronically. A comm circuit may use
any conventional protocol and/or circuits for communicating. A comm
circuit may communicate via any conventional network (e.g.,
internet, WAN, LAN). A comm circuit may receive information for
controlling a reader and/or the operations performed by the reader.
A processing circuit may receive information from a comm circuit. A
processing circuit may perform a function in accordance with
information received via a comm circuit. A processing circuit may
provide information for transmission to a comm circuit. A
processing circuit may control the operation of and/or cooperate
with the comm circuit to perform the functions of communication. A
processing circuit may perform all or some of the functions of a
comm circuit.
A processing circuit may provide a report. A report may include an
electronic notice, an audible sound, a flashing light, and/or a
printed message. An electronic notice may include a packet of data
for communication via a conventional network, a text message for
communication via a conventional cell phone network, and/or an
electronic signal that conveys information. Subject matter of a
report may include a notice of detected moisture; a notice of no
detected moisture; a notice of a fault of the reader; a notice of
proper electrical coupling of a reader to a moisture sensor, a
position of detected moisture relative to a moisture sensor, a
position of detected moisture relative to a substrate, an area of
detected moisture and/or a status (e.g., energy level) of a power
supply. A report may be provided to a comm circuit for
transmission.
A contact provides a surface for mechanical and/or electrical
coupling. A contact of a moisture sensor may electrically couple to
a conductor of the moisture sensor for providing electrical energy
to a conductor. A contact of a moisture sensor may mechanically
couple to a substrate or to any layer positioned over and/or under
the conductors of a moisture sensor. A reader may include contacts
(e.g., prongs, teeth) for coupling to the contacts of a moisture
sensor.
A reader may mechanically and/or electrically couple to a moisture
sensor. A reader may mechanically couple to a substrate to
establish a mechanical and/or electrical coupling with a moisture
sensor. Contacts of a reader may mechanically and/or electrically
couple to contacts of a moisture sensor. In the absence of contacts
on a moisture sensor, a reader may directly mechanically and/or
electrically couple to the conductors of a moisture sensor. A
reader may removeably (e.g., detachably) couple to a substrate
and/or a moisture sensor. A processing circuit may electrically
couple to a moistures sensor via the coupling of the reader to the
moisture sensor.
Moisture sensor 160 may include conductors 150 and contacts 140.
Conductors 150 may include two or more conductors. Contacts 140 may
include three or more contacts. Conductors 150 and contacts 140 may
conduct an electrical current. At least two contacts are
electrically coupled to one of the conductors preferably one
contact at each end of the conductor. Contacts 140 may be
positioned at any location on pad 170. Preferably, contacts 140 are
positioned proximate to each other in the vicinity of an edge of
pad 170 to facilitate coupling to reader 120. Conductors 150
cooperate with pad 170 to detect the presence of moisture. Contacts
140 cooperate with reader 120 for removeably coupling reader 120 to
pad 170 and/or moisture sensor 160. Reader 120 electrically couples
to moisture sensor 160 to detect whether moisture is present in
moisture sensor 160 and/or in pad 170. A reader may report,
electronically, audibly, and/or visually, a result of
detecting.
Moisture sensor 260 of FIGS. 2-5 includes an implementation of
conductors, contacts, and a substrate. Substrate 270 performs the
functions of a substrate discussed herein. Substrate 270 includes
an absorbent material for absorbing a liquid. Substrate 270
receives and absorbs liquids. Substrate 270 may cooperate with an
additional layer (e.g., 510) of absorbent material positioned over
conductors 250 and 252 to absorb liquid.
As a portion of substrate 270 becomes saturate with liquid, the
liquid spreads across substrate 270, so that the area of substrate
270 that holds liquid increases. Conductors 250-252 are integrated
into or are mechanically coupled to substrate 270. As discussed in
further detail below, the absorbent material of substrate 270
cooperates with conductors 250-252 to capture liquid in a manner
that conductors 250-252 in cooperation with reader 120 may detect
the presence of the liquid.
Mechanically coupling conductors 250 and/or 252 to substrate 270
may include using a conventional sewing machine to sew a conductive
thread to substrate 270 so that the conductive thread performs the
functions of conductors as discussed herein.
A conductor may be formed of any conductive material. Conductive
material may include a metal and/or semi-conductive (e.g.,
semi-conductor) material. The structure (e.g., form, length,
height, width) of a conductor includes any conventional structure
of a conductor. Structures of a conductor may include the form of a
conventional wire, a thin-film conductor, a thick-film conductor,
and a deposited (e.g., printed, formed by deposition) conductive
material.
A conductor has an impedance (e.g., resistance). The impedance of a
conductor may include the bulk resistivity of the material of the
conductor (e.g., .rho., rho), sheet resistance of the material of
the conductor, and a total resistance of the conductor.
Conductors whose impedance is described in terms of a sheet
resistance may have a width, a thickness, a length (e.g., volume),
and a bulk resistivity .rho. (i.e., rho). Sheet resistance Rs is
defined as the resistivity .rho. divided by the thickness of the
conductor. Sheet resistance is expressed as .OMEGA./.quadrature.
(i.e., ohms/square, ohms per square). In equation form, Rs is:
Rs=.rho./t, Equation 1 where:
.rho. (e.g., rho) is the bulk resistivity of the conductor, as
discussed above.
t is the thickness of the conductor.
An example of a conductor having a sheet resistance and a thickness
shown in FIG. 3. Conductor 252 has width 332, thickness 342, and
length 310. Conductor 250 includes three different sections. A
first section of conductor 250 has width 330, thickness 340 and
length 320. A second section has width 334, thickness 344, and
length 320. A third section has width 336, thickness 346, and
length 322. Some or all of widths 330, 334, 336; thicknesses 340,
344, and 346; and lengths 320 and 322 may be the same or different.
The total length of conductor 250 is the sum of the lengths of its
sections (i.e.: 320+320+322).
The impedance of a conductor having a sheet resistance or an
impedance per unit length is proportional to a length of the
conductor, so the total resistance of conductors 250 and 252 is
proportional to their respective lengths.
A total resistance of a conductor may be determined (e.g.,
calculated) in accordance with the sheet resistance of the material
of the conductor, a width of the material of the conductor, and a
length of the material of the conductor. The total resistance of a
conductor may be expressed as: R=Rs*(L/W), Equation 2 where:
Rs is the sheet resistance of the material of the conductor, as
provided above in Equation 1.
L is the length of the conductor.
W is the width of the conductor.
The total resistance of conductors 250 and 252 may be calculated
as: R252=Rs252*(length 310/width 332); and R250=(Rs250*(length
320/width 330))+(Rs250*(length 320/width 334))+(Rs250*(length
322/width 336)).
Rs252 is the sheet resistance of the material that forms conductor
252. Rs250 is the sheet resistance of the material that forms
conductor 250. For the sake of simplicity, assume that all sections
of conductor 250 are formed of the same material so that the sheet
resistance of the material of each section is the same. The
material of conductor 250 may be different from the material of
conductor 252, so sheet resistance Rs250 may be different from
sheet resistance Rs252.
R252 is the total impedance of conductor 252 along its entire
length, which is length 310. R250 is the total resistance of
conductor 250 along its entire length, which is length 320+length
320+length 322.
The total impedance (e.g., resistance) of a conductor may also be
determined using the relationship V=IR. A voltage of a known
magnitude may be applied across a conductor. The current provided
through the conductor by the source of the voltage may be measured.
The total resistance of the conductor may be calculated as R=V/I.
Alternatively, a current of a known magnitude may be provided
through the conductor and the magnitude of the voltage across the
conductor measured. The total resistance of the conductor may be
calculated using the above formula.
According to various aspect of the present invention, the material
and/or structure (e.g., width, thickness, length) of conductor 250
is different from the material and/or structure of conductor 252 so
that the total impedance of conductor 250 is different from the
total impedance of conductor 252. Preferably, the total impedance
of conductor 250 is greater than the total impedance of conductor
252. The difference in impedance may result from not only from
differences in structure, but also in differences in bulk
resistivity because the conductors are formed of different
materials (e.g., Al, Cu, C).
Preferably, the sheet resistance of conductor 250 is greater than
the sheet resistance of conductor 252 so the per square impedance
of conductor 250 is greater than the per square impedance of
conductor 252. In an implementation, the impedance per square of
conductor 250 is greater than the impedance per square of conductor
252. In another implementation, the impedance per square of
conductor 250 is at least two to three times greater than the
impedance per square of conductor 252. In another implementation,
the impedance per square of conductor 250 is at least five to ten
times greater than the impedance per square of conductor 252.
Further, the total resistance of the entire length of conductor 250
is greater than the total resistance of the entire length of
conductor 252.
The impedance per square of conductor 250 may also be greater than
the impedance of any liquid that may be absorbed by substrate 270
so that the liquid is positioned between and contacting conductor
250 and 252.
For example, referring to FIGS. 4 and 5, liquid 410 has been
absorbed, at least partially, by substrate 270 so that liquid 410
is positioned between (e.g., across, bridging) conductor 250 and
252. Liquid 410 is conductive so it functions as impedance R410
between conductor 250 and 252. The magnitude of impedance R410
depends on the distance between conductors 250 and 252 and the bulk
resistance of the liquid between the conductors.
To aid in detecting liquid, the distance between conductors 250 and
252 is uniform along the lengths of the conductors. An exception at
the interior corners of conductor 250 where conductor 250 turns at
90 degree angles. In this implementation, the distance between
conductor 240 and conductor 252 ranges between one times the
distance along a straight portion of the conductors and 1.414
(e.g., root 2) times the distance in the corners of conductor 250.
Conductor 250 may be implemented as a semicircle so that the
distance between conductor 250 and 252 is the same at all points
along the conductors.
Distance 280 between conductors 250 and 252 sets a maximum value
for R410 of a liquid having a particular bulk resistance. For
example, if the distance between conductor 250 and 252 is one
centimeter, the magnitude of resistance R410 will be between 150
and 400 ohms for a material having a bulk resistance of between
150-400 ohms-centimeter (i.e.: .OMEGA.-cm).
In another example, for a spacing (e.g., 280) of 0.2 centimeters
between conductor 250 and 252, the magnitude of R410 for a liquid
having a bulk resistance of between 150-400 .OMEGA.-cm would be in
the range of 30 to 80 ohms. The sheet resistance of conductor 250
may be less than, equal to or greater than the bulk resistance of
the liquid. For example, the sheet resistance of conductor 250 may
be in the range of less than 1 ohms per square to 800 ohms per
square. In an implementation, the sheet resistance of conductor 250
is 0.01 ohms per square. In another implementation, the sheet
resistance of conductor 250 is 800 ohms per square.
In an implementation, the distance between conductors 250 and 252
is such that the maximum value of R410 is less than the resistance
of the shortest portion of conductor 250 that a current may travel
through before reaching impedance R410. For example, when a current
travels loop 480, the current travels from contact 240 through
portion 440 of conductor 250 before reaching impedance R410. The
total resistance of portion 440 is greater than the magnitude of
the impedance of R410. Liquid 410 may be positioned closer to
contact 240, so the portion of conductor 250 through which the
current travels may be much shorter than portion 440. Preferably,
the distance between conductor 250 and 252 and the sheet resistance
of conductor 250 ensures that the impedance of any portion of
conductor 250 is at least five to ten times greater than the
impedance of any liquid between conductors 250 and 252.
For example for this implementation, for a spacing (e.g., 280) of
0.2 centimeters between conductor 250 and 252, the magnitude of
R410 for a liquid having a bulk resistance of between 150-400
.OMEGA.-cm would be in the range of 30 to 80 ohms. The sheet
resistance of conductor 250 is in the range of 400 to 800 ohms per
square, preferably 800 ohms per square.
In the same implementation, the impedance per square of conductor
252 may be less than the impedance of any liquid positioned between
conductor 250 and 252. As discussed above, for a spacing of 0.2
centimeters between conductor 250 and 252, the magnitude of R410
for a liquid having a bulk resistance of between 150-400 .OMEGA.-cm
would be in the range of 30 to 80 ohms. The sheet resistance of
conductor 252 may be in the range of 3 to 8 ohms per square,
preferably 3 ohms per square or less.
The spacing between conductor 250 and 252 may depend on the amount
of liquid expected to be caught (e.g., captured, absorbed) by a
particular substrate or the minimum amount of liquid that should be
detected for a particular substrate or application. The
relationship between the sheet resistance of conductors 250 and 252
and the spacing between the conductors discussed above may hold
regardless of spacing.
The spacing between and sheet resistance of conductors 250 and 252
may be different for liquids that have different bulk
resistance.
Reader 120 provides electrical signals and measures electrical
signals to determine the portions of conductors 250 and 252 that
lead to or from the impedance of a liquid positioned between
conductors 250 and 252. Reader 120 may detect the length of the
portion of conductor 250 and/or 252 between contacts 240-244 and
impedance R410 of liquid 410. Determining the location of liquid
410 along the length of conductor 250 and/or 252 from contacts
240-244 provides information of the position of liquid 410 relative
to conductors 250 and 252 and contacts 240-244. However, because
the sheet resistance of conductor 250 is higher than the sheet
resistance of conductor 252, reader 120 may more accurately
determine the position of liquid 410 with respect to conductor 250
rather than conductor 252 because the change in impedance along
conductor 250 is greater than the change in impedance along
conductor 252 and therefor easier to detect (e.g., measure).
Accordingly, because reader 120 may determine the length of the
portion of conductor 250 between contact 240 and/or 244 and liquid
410, reader 120 may determine position of liquid 410 relative to
conductor 250.
Reader 120 may include clip 600, shown in FIG. 6, for mechanically
and electrically coupling to moisture sensor 260 and/or substrate
270. Clip 600 may include teeth 670-674 for coupling mechanically
and electrically to contacts 240-244 of moisture sensor 260. Teeth
670-674 are formed of a conductive material so that teeth 670-674
may perform the function of contacts as discussed above. Support
614 may mechanically (e.g., friction, pressure) couple to substrate
270 to hold (e.g., maintain, retain) clip 600 mechanically and
electrically coupled to substrate 270 and moisture sensor 260, in
particular contacts 240-244. Clip 600 may include a resilient force
(e.g., spring, magnet) that forcefully moves upper jaw 610 toward
lower jaw 612 so that teeth 670-674 move toward and are maintained
proximate to support 614. A force (e.g., pressure) between teeth
670-674 and support 614 may mechanically couple clip 600 to
moisture sensor 260 and substrate 270. Physical contact of teeth
670-674 with contacts 240-244 (740-744, 940-944) may electrically
couple teeth 670-674 to contacts 240-244 (740-744, 940-944). Clip
600 may include more than three teeth for substrates that have more
than three contacts. Generally, clip 600 includes one tooth for
each contact.
Preferably, contacts 240-244 (740-744, 940-944) are positioned
proximate to each other and on the same edge of substrate 270 (770)
or pad 570 (970, 1370), so that clip 600 may be compact and
physically contact contacts 240-244 (740-744, 940-944) when
coupled.
Electrical contact of a first tooth of clip 600 with contact 240
(740) and a second tooth of clip 600 with contact 244 (744)
provides a circuit via conductor 250 (750) for reader 120 to
determine that it is electrically coupled to moisture sensor 260
(760). Upon coupling reader 120 to moisture sensor 260, reader 120
may provide a voltage across contacts 240 and 244 not only to
determine whether an electrical connection is established with
conductor 250, but also to determine an initial resistance of
conductor 250 prior to use of substrate 270 to absorb liquid.
The initial resistance of conductor 250 may be used to identify the
version (e.g., model number, make) the moisture sensor. The initial
resistance of conductor 250 may be measure by applying a voltage
across contacts 240 and 244 and measuring the resulting current. A
look-up table may be used to correlate the magnitude of the initial
impedance of conductor 250 to a model number of the moisture
sensor. As shown here, the physical layout (e.g., shape, width,
length) of the conductors may be different for various types of
moisture sensors. Knowledge of the layout of a moisture sensor may
provide information to permit correlation of the position of a
liquid with respect to a conductor to a position with respect to
the substrate and/or cover of the moisture sensor. Knowledge of the
layout of the moisture sensor may provide information for
interpreting the voltages and currents measured from the moisture
sensor.
The initial value of conductor 250 may be unique, within a range,
for each different version of moisture sensor. A reader may detect
the initial value and correlate the initial value to information
for reading and interpreting electrical and physical information
about the moisture sensor. A reader may store such information for
a variety of moisture sensors or the reader may transmit the
initial value of conductor 250 to a server and receive information
that corresponds to that version of the moisture sensor. A reader
may provide (e.g., transmit) the version number of the moisture
sensor. A reader may provide the version number of the moisture
sensor each time it transmits information gathered by the reader so
that the information may be construed in light of the version of
the moisture sensor.
The physical structure of teeth 670-674 of clip 600, including
absolute teeth position, teeth position relative to each other,
length, and width. Teeth 670-674 may be positioned relative to each
other and relative to contacts 240-244 so that the proper placement
of any two teeth in contact with two contacts of contacts 240-244
guarantees that the other tooth is properly coupled to its
respective contact. For example, tooth 672 is positioned between
teeth 670 and 674. While reader 120 is properly coupled to contacts
240-244, reader 120 may detect an electrical connection between
teeth 670 and 674 via conductor 250. Because of the physical
placement of tooth 672 between teeth 670 and 674, confirmation of
proper electrical coupling of teeth 670 and 674 by reader 120
guarantees that tooth 672 is properly coupled to contact 242.
Conductor spacing and/or position of contacts, whether three or
more, may be standardized for many types of substrates so that the
same clip may be used to contact to all of the substrate types.
Clip 600 includes pin 640 so that upper jaw 610 may be rotated away
from lower jaw 612 so that clip 600 may be decoupled, both
electrically and mechanically, from moisture sensor 260 (760) and
substrate 270 (770) or pad 570 (970, 1370). The force that moves
upper jaw 610 toward lower jaw 612 to couple clip 600 to moisture
sensor 260 (760) and substrate 270 (770) or pad 570 (970, 1370)
must be overcome to move upper jaw 610 away from lower jaw 612 to
release clip 600 from moisture sensor 260 (760) and/or substrate
270 (770) or pad 570 (970, 1370).
Teeth 670-674 may couple to conductors 630-634 of wires 620-624
respectively. Wires 620-624 may couple to processing circuit 122 so
that reader 120 is electrically coupled to moisture sensor 260 so
that reader 120 may perform the functions of a reader discussed
herein. Reader 120 may be small enough in size that reader 120 may
be integrated with clip 600 so that wires 620-624 are short or
replaced by some other type of electrical connection between
processing circuit 122 and teeth 670-674 that is suitable for a
circuit integrated into clip 600.
Clip 600 may have additional teeth for proper coupling to a type of
moisture sensor that has additional contacts. It is also possible
to have a clip with more teeth than contacts on a particular type
of moisture sensor. A subset of the teeth may couple to the
contacts of the moisture sensor. In the implementations discussed,
clip 600 has one tooth for each contact of a moisture sensor.
Because contacts may be positioned on top of a substrate and/or the
bottom of a substrate, clip 600 may have teeth on upper jaw 610
and/or lower jaw 612.
While reader 120 is electrically coupled to moisture sensor 260,
using clip 600 or any other type of conventional coupler, reader
120 may determine whether liquid is present on substrate 270 (770)
or pad 570 (970, 1370) and the location of the liquid with respect
to at least conductor 250 (750, 910/912, 1410/1414) and thereby
with respect to substrate 270 (770) or pad 570 (970, 1370).
Referring to FIGS. 2-5, to detect moisture 410 on substrate 270,
reader 120 may provide voltages across contacts 240-244, detect
currents, and use information about the magnitudes of the currents
and/or the voltages to determine a magnitude of an impedance of
moisture sensor 260. The detected impedance of moisture sensor 260
relates to whether moisture is present or absent from moisture
sensor 260. The magnitudes of the impedances further related to the
position of liquid 410 with respect to conductors 250 and 252, and
in particular with respect to conductor 250. If there is some type
of known correlation between the position of conductors 250 and/or
252 to substrate 270, reader 120 may further correlate the position
of moisture 410 to a position on substrate 270.
In an implementation, reader 120 may perform the following
operations to detect moisture 410 and to determine the position of
moisture 410 relative to conductors 250 and/or 252. In this
example, assume that liquid 490 is not present. Reader 210 applies
a voltage across contacts 240 and 242 to induce a current through
loop 480. Because the impedance per square of conductor 250 is
greater than the impedance per area of moisture 410, any current
provided by reader 120 travels along portion 440 of conductor 250
until it reaches the lower impedance of moisture 410. The current
traverses R410 of moisture 410 to the even lower impedance of
conductor 252. The current returns to reader 120 along portion 460
of conductor 252. Reader 210 calculates the impedance (e.g.,
magnitude of impedance) of loop 480.
The distance 280 between conductors 250 and 252 is known by reader
120. Further, reader 120 has information as to the range of
impedances of the liquids that might be present in substrate 270.
Knowing the distance between conductors 250 and 252, reader 120 may
determine (e.g., calculate) a range of impedances for R410. The
impedance of R410 may be subtracted from the total impedance of
loop 480 to determine the resistance of portion 440 of conductor
250 and portion 460 of conductor 252; however, since the impedance
of conductor 252 is much lower than the impedance of conductor 250,
the impedance that remains after the impedance of R410 is
subtracted is predominantly the impedance of portion 440 of
conductor 250.
Reader 210 applies a voltage across contacts 242 and 244 to induce
a current through loop 482, again assuming that liquid 490 is not
present. Because the impedance per square of conductor 250 is
greater than the impedance per area of moisture 410, any current
provided by reader 120 travels along portion 450 of conductor 250
until it reaches the lower impedance of moisture 410. The current
traverses R410 of moisture 410 to the even lower (e.g., lesser)
impedance of conductor 252. The current returns to reader 120 along
portion 460 of conductor 252. Reader 210 calculates the impedance
of loop 482.
As discussed above, the reader has calculated a range of impedances
for the likely liquids in substrate 270. The impedance from R410
may be subtracted from the impedance of loop 482 to determine the
impedance of portions 460 and conductor 252 and 450 of conductor
250. Because the impedance per square of conductor 250 is higher
than the impedance per square of conductor 252, the impedance after
subtracting R410 is predominantly the impedance of portion 450 of
conductor 250.
As discussed above, the majority of the magnitude of the impedance
of loop 480 and 482 is due to the impedance of conductor 250.
Reader 210 may use the ratio of the impedance of loop 480 to the
total initial impedance of conductor 250 to determine the distance
from contact 240 to the position of moisture 410. Reader 120 may
also use the ratio of the impedance of loop 480 and loop 482 after
subtraction to the total initial impedance of conductor 250 to find
the distance of liquid 410 from contacts 240 and 244
respectively.
For example, if the ratio of the impedance of loop 480 or portion
440 to the total initial impedance of conductor 250 is about 0.25,
then the position of moisture 410 is about a quarter of the total
length of conductor 250 from contact 240. The length of portion 440
is about one-quarter of the total length of conductor 250. If the
ratio of the impedance of loop 482 or portion 450 to the total
initial impedance of conductor 250 is about 0.75, then the position
of moisture 410 is about three-quarters of the total length of
conductor 250 from contact 244. The length of portion 450 is about
three-quarters of the total length of conductor 250.
The position of liquid 410 along the length of conductor 250 from
contacts 240 and 244 provide information as to the position of
liquid 410 with respect to conductor 250 and contacts 240 and
244.
The width, or spread, of moisture 410 may be determined by
detecting the difference between the position of moisture 410 from
contact 240 and the position of moisture 410 from contact 244. For
example, if the distance from contact 240 and from contact 244 to
moisture 410 is about 25% and 45% of the length conductor 250
respectively, moisture 410 has spread along about 20% of the length
of conductor 250. It is also possible that moisture 410 is
positioned at the 25% point from contact 240 and moisture 490 is
positioned at the 45% point from 244 with no liquid in between
liquid 410 and liquid 490.
The initial impedance of conductor 250 may be detected by reader
120 while reader 120 is coupled to moisture sensor 260 at contacts
240-244 prior to deployments of moisture sensor 260 or prior to
absorbing any liquid by substrate 270. Another method for
determining the initial impedance of conductor 250 is for the
impedance to be measured and/or characterized at manufacture and
such information provided to reader 120 for example via comm
circuit. The magnitude of the initial impedance may be recorded by
reader 120 whether it is measured by reader 120 or provided to
reader 120. Reader 120 may use the stored initial impedance to
perform calculations such as detecting the position and/or spread
of moisture as discussed herein.
Reader 120 may calculate and record, from time-to-time, the
position and spread of liquid 410. Reader 120 may use historical
information to determine a rate of spreading. Reader 120 may
provide a notice in accordance with a rate of spread as to a
possible time that substrate 270 may need to be replaced. The
notices provided by reader 120 may be routed to a care giver to
provide the care giver information as to when substrate 270 may
need to be changed due to the amount and/or spread of liquid in
substrate 270. Reader 120 may provide an estimated time of day, in
accordance with an calculated rate of spread, when the substrate
(e.g., pad) should likely be changed.
Because the sheet resistance of conductor 250 is higher than the
impedance per area of the liquid and the sheet resistance of
conductor 252, the impedance of a loop (e.g., 480, 482) relates
more directly to impedance of the portion of conductor 250 in the
loop than to the impedance of the liquid or the impedance of the
portion of conductor 252 in the loop. Further, as discussed above,
the estimated impedance of the liquid may be subtracted from the
impedance of a loop to provide a resulting impedance that is more
closed related to the impedance of the portion of conductor 250 in
the loop.
Because the impedance of conductor 250 is measured from both end
portions of conductor 250 via loop 480 and 482, the edges of
moisture 410 may be detected and related to a length along
conductor 250. If the length of conductor 250 relates to positions
on substrate 270, the measurements with respect to conductor 250
from contact 240 and 244 may relate to positions on substrate 270,
and therefore to an area of substrate 270.
Conductors may mechanically couple to a substrate. The spacing
between conductors may be uniform and/or variable. Preferably, the
spacing between conductors is uniform so that reader 120 may
estimate the impedance of potential liquids between conductors.
However, because reader 120 can detect a distance along a conductor
to a position of a liquid, reader 120 may also use stored
information to look up the distance between the conductors at the
position of the liquid. Knowing the distance between the conductors
at the position of the liquid enables reader 120 to estimate the
impedance of the liquid at that position. So, reader 120 may
estimate the impedance of a liquid even though the distance between
the conductors varies. As discussed above, conductor spacing may
relate to the conductive properties of a liquid so that that the
impedance through a liquid between conductors is within a desired
range.
The properties of the material used to form a substrate may promote
a uniform (e.g., even) spread of a liquid through the substrate and
around (e.g., between) the conductors. The absorbency of a
substrate may promote uniform spread of a liquid across the
substrate and around conductors as opposed to the liquid reaching a
conductor and flowing nearly exclusively along the length of the
conductor.
A substrate may be a part of a pad that encloses (e.g., envelopes)
a moisture sensor. A pad may be formed of layers of materials. The
layers of the materials may be the same and/or different. One or
more layers of a pad may be sterile. A conductor of a moisture
sensor may be positioned in or on the substrate of a pad, another
layer, or alternate between layers. A pad may include one or more
layers that cover the substrate and/or conductors of the moisture
sensor. The one or more layers may be referred to as a cover. Any
number of layers may be positioned above and/or below the
conductors of the moisture sensor. Conductors of a moisture sensor
may be positioned on the same side of the same layer, different
sides of the same layer, or on different layers of the pad. A
conductor may couple (e.g., affix, attach, fasten, connect) to the
substrate or any layer of a pad using any conventional method
(e.g., printing, deposition, mechanical, adhesive, sewing). A
substrate or any other layer of a pad may insulate the conductors
from each other in the absence of a liquid.
A layer of a pad may absorb or resist the penetration of liquid. A
layer may facilitate the uniform spread of a liquid through the pad
and/or substrate. A material of a layer may retard the movement
(e.g., spread) of a liquid. A layer may influence (e.g., direct,
channel) the movement of a liquid through and/or across the pad
and/or substrate. A layer may facilitate movement of a liquid
toward and/or between conductors.
A layer of a pad may be formed of an absorbent and/or a
non-absorbent material. A layer formed of a non-absorbent material
may perform the function of retaining liquids in the pad as opposed
to allowing the liquids to exit (e.g., leak from) the pad. A layer
may function as an insulating layer for applications that may
benefit from an insulated pad. A layer may perform the function of
a protective barrier. A pad may be disposable after use.
A layer of a pad may provide a surface for mounting electronic
circuits, conductors for power, an antenna for communication,
and/or data buses associated with a moisture sensor and/or a
reader. A layer of a pad provides a surface for the mounting of
contacts for coupling to a reader. A layer of a pad may include a
non-absorbent layer (e.g., polyethylene terephthalate,
biaxially-oriented polyethylene terephthalate, mylar, melinex,
hostaphan) to which the conductors, contacts, and any associated
electronics are coupled. An absorbent layer may be placed over the
non-absorbent layer.
For example, the pad of FIGS. 2-4 is shown as including a single
layer substrate 270. The substrate 270 is positioned under
conductors 250 and 252. No layer is shown as positioned over the
conductors. Omitting a layer over conductors 250 and 252 simplifies
the drawing for description, but may not be suitable for a
substrate in actual use. An additional layer may be added to
substrate 270 that covers conductors 250 and 252, such as cover
510. Such a layer may be absorbent. Cover 510 may be non-conductive
when it has not absorbed a liquid. Pad 570 further includes base
530 under substrate 270. Base 530 may be non-absorbent so that
liquid absorbed by substrate 270 and cover 510 does not exit pad
570.
Conductors of a moisture sensor may be laid out and/or positioned
on a layer of a pad in any pattern. Regardless of the pattern, the
principles discussed above for detecting the position and spread of
moisture with respect to the conductors of the moisture sensor
apply. Generally, as discussed above, it is a simplifying practice
to keep the spacing between the conductors of the moisture sensor
equally spaced from each other along their lengths, but as further
discussed above constant spacing is not a requirement. Further, as
discussed below, it is possible to protect portions of a conductor
from moisture (e.g., waterproof) in areas where it is undesirable
for liquid to create a circuit using those portions of the
conductors. Conductors of a moisture sensor may further be laid out
in a pattern that divides a substrate into zones.
For example, conductors 750 and 752 of moisture sensor 760 are
arranged on a surface of substrate 770 in a serpentine pattern.
Contacts 740-742 are positioned along the same edge of substrate
770 proximate to each other and perform the functions and include
the characteristics of contacts 240-244 discussed above. Conductors
750 and 752 perform the functions and include the characteristics
of conductor 250 and conductor 252 discussed above. Moisture sensor
760 performs the functions of a moisture sensor discussed above.
Substrate 770 performs the functions of a substrate discussed
above. Substrate 770 may be a part of a pad that includes
additional layers as discussed with respect to substrate 570 such
as an absorbent layer positioned over conductors 750 and 752 and a
non-absorbent layer positioned under substrate 770.
Substrate 770 includes water (e.g., liquid, moisture) resistant
layer (e.g., covering) 771. Layer 771 covers a portion of conductor
750 and substrate 770 so that moisture cannot bridge between the
portion of conductor 750 that is covered by layer 771 and an
adjacent portion of conductor 750. Covering portions of conductors
750 and 752 with layer 771 shields them from moisture so that
moisture detection is accomplished in the areas of substrate 770
that are not protected (e.g., shielded) by layer 771. Layer 771
defines inactive portions of moisture sensor 760 while the portions
of moisture sensor 760 not covered by layer 771 are the active
portions of moisture sensor 760. Preferably, moisture cannot be
detected in inactive portions, while moisture may be detected in
active portions.
The serpentine pattern of conductors 750 and 752 divide substrate
770 into zones. The vertical, with respect to the orientation of
FIGS. 7 and 8, portions of conductors 750 and 752, define zones
720-726. Zones may be used to relate the position of a liquid along
conductors 750 and 752 to an area of substrate 770. A reader may
include information that translates the position of the liquid with
respect to conductors 750 and 752 into information regarding the
zone where liquid is positioned. Substrate 770 may include indicia
for an operator to relate zone information reported by a reader to
the physical layout of substrate 770. For example, each zone of
substrate 770 may have a different identifying color or printed
indicator on the outside of substrate 770 so that an operator may
identify the zone where liquid is detected by the reader. An
operator may use zone information as related to substrate 770 to
determine the extent of the spread of the liquid.
Reader 120 may use the same techniques discussed above for
detecting the position of moisture with respect to conductors 750
and 752. As discussed above, reader 120 may provide a voltage
across contacts 740-744 and detect the currents induced in loops
780 and 782 along conductors 750 and 752 and through impedance R710
of moisture 710. As discussed above, the magnitude of the impedance
of loop 780 may be compared to the total magnitude of the initial
impedance of conductor 750 to determine the position of moisture
710 with respect to conductor 750. Reader 120 may correlate the
position of moisture 710 to a zone.
Because of the water resistant nature of layer 771, the path
through contact 740 to moisture 710 will always be longer than the
path through contact 744 to moisture 710. Reader 120 may have
stored information regarding the physical layout of conductor 750
and the portions covered by layer 771, so that it may determine the
position of moisture 710. An operator may provide the model number
of a substrate to reader 120, so reader 120 may use stored
information regarding the substrate for position, spread, and zone
calculations.
In the implementation of FIG. 7, the spacing between conductor 750
and conductor 752 is uniform along the lengths of the
conductors.
In an implementation, pad 170 containing moisture sensor 160 may be
deployed (e.g., positioned) in an area where moisture may cause
significant damage, but areas that are checked infrequently, such
as under a sink, or areas that are difficult to access, such as
under an appliance (e.g., washing machine, refrigerator).
For example, sensor roll 800 includes pad 810 that may be rolled
around itself like a roll of masking tape prior to deployment, for
storage, and/or for shipping. One side of pad 810 may include an
adhesive for retaining pad 810 in the rolled shape prior to use
and/or for retaining pad 810 in position when unrolled and placed
in position to detect moisture.
Pad 810 may be produced with standardized widths and lengths for
particular applications. Such widths and lengths may relate to the
standard sizes of appliances or kitchen sinks. When extended, pad
810 conforms to the surface upon which it is placed. Pad 810
includes absorbent cover 972 and absorbent substrate 970. Pad 810
may further include a non-absorbent base beneath, with respect to
FIG. 9, substrate 970.
Conductors 910-914 are positioned on and coupled to substrate 970.
Conductors 910-914 are covered by cover 972. Contacts 940-944 and
contacts 1240-1244 mechanically and electrically couple to
conductors 910-914 at respective ends of pad 810. Contacts 940-944
are positioned at one end of pad 810 and contacts 1240-1244 at the
opposite end of pad 810. Although contacts 940-944 and 1240-1244
are shown spread out along width 830 of pad 810, contacts 940-944
and 1240-1244 may be closely spaced to one edge of pad 810 to
permit reader 120 to couple to pad 810 using a mechanical coupler
of relatively small size compared to the width of the pad. Reader
120 may couple to contacts 940-944 or 1240-1244 using any type of
conventional mechanical and/or electrical connection including clip
600 disclosed above.
Conductor 910 is covered by non-absorbent (e.g., impervious to
liquid, waterproof) layer 960 that performs the functions of layer
771 discussed above. Layer 960 prevents or delays establishing a
circuit between conductor 910 and 912. In the implementation shown,
if substrate 970 is absorbent, liquid may eventually pass under
layer 960 to establish an electrical connection between conductor
910 and conductor 912. If the substrate is non-absorbent or less
absorbent, a liquid may not be able to establish an electrical
connection between conductor 910 and 912 along the length of layer
960.
For example referring to FIG. 10, liquid 980 establishes an
electrical connection between conductor 912 and 914 via impedance
R1010, but not between conductors 910 and 912 or 910 and 914.
Conductors 912 and 914 may have serpentine pattern so that
conductors 912 and 914 cover more of the area of pad 810 across
width 830. As discussed above, the serpentine pattern may establish
zones for detecting and reporting the area of moisture with respect
to pad 810. In the implementation of pad 810, space 1110 between
conductor 912 and 914 is constant. As discussed above the
separation of conductor 912 from 914 need not be constant.
Reader 120 may couple to contacts 940-944 at one end of roll 810,
end portion 1210, or contacts 1240-1244 at the other end of roll
810, end portion 1212. Shunt 1220 (e.g., bridge, cap) couples
between conductor 910 and 912 at the end not used by reader 120.
Shunt 1220 electrically couples conductor 910 to conductor 912. A
cap may perform the function of a shunt. Coupling conductor 910 to
conductor 912 with shunt 1220 permits reader 120 to detect that it
is electrically coupled to conductors 910 and 912 at the other end
of pad 810. Shunt 1220 may mechanically and electrically couple to
conductors 910 and 912. Shunt 1220 may further mechanically couple
to pad 810 to maintain the mechanical and electrical coupling with
conductors 910 and 912. Shunt 1220 may mechanically couple to
conductors 910 and 912 and pad 810 using any conventional coupling
structures. Shunt 1220 may electrically couple to conductors 910
and 912 using any conventional coupling structures.
Conductor 912 has a higher impedance per unit length than the
impedance per unit length of any liquid that may penetrate pad 810.
The difference in impedance between conductors 910 per unit length
and any liquid that may penetrate pad 810 may be at least five
times. Conductor 914 has a lower impedance per unit length than the
impedance per unit length of any liquid that may be absorbed by pad
810. The difference in impedance between any liquid that may
penetrate pad 810 and conductor 914 may be at least five times.
Conductor 910 may have an impedance per unit length that is greater
than the impedance of any liquid that may penetrate pad 810 or an
impedance per unit length that is less than any liquid that may
penetrate pad 810. Conductors 910 and 912 may have the same
impedance per unit length. Conductors 910 and 912 may different
impedances per unit length. In an implementation where the
impedance per unit length of conductor 910 is greater than the
impedance of any liquid, conductors 910 and 912 have the same
magnitude of impedance per unit length. In an implementation where
the impedance per unit length of conductor 910 is less than the
impedance of any liquid, conductor 910 has a magnitude of impedance
that is at least five times less than the impedance of any liquid
that may penetrate pad 810, preferably an order of magnitude
less.
When conductors 910 and 912 are electrically coupled together and
conductors 910 and 912 have the same magnitude of impedance per
unit length, conductors 910 and 912 function in the same manner as
conductor 250 or conductor 750 discussed above. When conductors 910
and 912 are electrically coupled together and conductor 912 has an
impedance that is greater than any liquid that may penetrate pad
810 and conductor 910 has an impedance that is less than any liquid
that may penetrate pad 810, conductor 912 functions in the same
manner as conductor 250 or conductors 750 disclosed above.
Conductor 914 functions in the same manner as conductor 252 and 752
disclosed above.
In an implementation, reader 120 may include coupler 1250 for
coupling to contacts 940-944 or contacts 1240-1244. Coupler 1250
may include any conventional structures for coupling to contacts
940-944 or contacts 1240-1244 and/or pad 810. Coupler 1250 may
include protrusions 1260-1264 for electrically coupling to contacts
940-944 respectively or contacts 1240-1244 respectively. Reader 120
may provide a voltage across protrusions 1260 and 1262. Upon
applying a voltage, if reader 120 detect a current, reader 120
detects that it is properly coupled to contacts 940 and 942
respectively or contacts 1240 and 1242 respectively, assuming that
shunt 1220 has been properly coupled to contacts 940 and 942 or
contacts 1240 or 1242 at the opposite end of pad 810. As disclosed
above, preferably when coupler 1250 detects that it is properly
coupled to contacts 940 and 942 or 1240 and 1242, contact 1264 is
also properly coupled to contact 944 or 1244 by default.
When liquid 980 is absorbed by pad 810, liquid 980 establishes an
impedance, for example impedance R1010, between conductor 912 and
914. Even though liquid 980 may be absorbed by pad 810 in the
vicinity of conductor 910 and between conductors 910 and 912, the
likelihood of developing an impedance through the liquid between
conductors 910 and 912 is significantly reduced if not entirely
eliminated by layer 960 which resists the penetration of liquid 980
to the point of contact with conductor 910.
The methods disclosed above may be used to determine the location
of liquid 980 with respect to at least conductor 912. Reader 120
may store information for correlating the position of the liquid
with respect to conductors 912 and/or 914 to a position with
respect to pad 810.
Because contacts 940-944 are positioned at end portion 1210 of pad
810 and contacts 1240 to 1244 are positioned at the opposite end
portion 1212, reader 120 and shunt 1220 may be coupled to the
contacts only at the extremities of pad 810, so pad 810 is a fixed
length, and as discussed above, may be produced in lengths that are
suitable for particular applications.
Pad 1300, referring to FIG. 13, is a pad that may be deployed in
lengths (e.g., segments) that are less than the total length of pad
1300. Pad 1300 may have width 1330. Pad may have length 1380. Pad
1300 includes substrate 1370 and cover 1372. Pad 1300 performs the
functions of pad 810 disclosed above. Substrate 1370 and cover 1372
perform the functions of substrate 970 and cover 972 discussed
above.
Length 1380 of pad 1300 may be subdivided into segments 1360. The
location of each segment may be indicated on the pad. A line
printed on the pad may indicate segment boundaries. Various
segments 1360 may be of the same length or different lengths. One
or more segments 1360 may be deployed for a use. Segments that are
not deployed for a use may be cut away from the segments that will
be deployed for a use. A pad may be cut at an indicated segment
boundary. Cutting a pad cuts the cover, the conductors, the
substrate, and any other layer of the pad.
Tear-away (e.g., removable) portions 1340 and 1342 are positioned
at the end portion of each segment 1360 (e.g., proximate to a
segment boundary). Removing tear-away portions 1340 and 1342
exposes the conductors of pad 1300 so that a reader and a shunt
(e.g., cap) may be coupled to the ends of the segments.
For example, pad 1300 may be cut in any conventional way (e.g.,
knife, scissors) at any segment termination line (e.g., boundary)
1350. The portion cut from length 1380 of pad 1300 may include one
or more segments. Tear-away portions 1340 and 1342 are removed from
each end of the portion to expose conductors 910-914. Tear-away
portion includes a portion of cover 1372. Tear away portions 1340
and 1342 may be prepared in any conventional way for separation
from substrate 1370; however, the integrity of layer 1360 should be
left substantially intact so conductor 910 is protected from liquid
in the portions of pad 1300 where tear-away sections are not
removed. Further, the integrity of cover 1372 over conductors 912
and 914 in the portions of pad 1300 where tear-away sections are
not removed should be left substantially intact so that liquid may
bridge between conductors 912 and 914 as cover 1372 and/or
substrate 1370 absorb liquid.
Removing tear-away portions 1340 and 1342 exposes the conductor
910-914 for coupling a reader and a shunt at respective ends of the
pad as discussed above. Read 120 may electrically couple to
conductors 910-914 at one end of the portion in any conventional
manner while shunt 1220 may couple to conductors 910 and 912 at the
other end of the portion.
End caps (e.g., cap) may also be used to perform the functions
shunting (e.g., electrical coupling) and mechanical coupling to
facilitate coupling a reader to conductors 910-914. An end cap may
be referred to as a cap. An end cap may include conductors for
electrically coupling to one or more of conductors 910-914. End
caps may include conductors or taps for providing access to
electrical conductors 910-914 to establish an electrical
coupling.
For example, shunt end cap 1500 may be positioned over one exposed
end of pad 1300 so that conductor 1510 electrically couples to
conductors 910 and 912. Conductor 1510 physically contacts
conductors 910 and 912 to establish electrical contact. Surface
1530 of shunt end cap 1500 contacts surface 1410 of pad 1300.
Surface 1530 may include an adhesive to retain conductor 1510 of
shunt end cap 1500 mechanically and electrically coupled to
conductors 910 and 912 of pad 1300. Shunt end cap 1500 may be
positioned on either end of pad 1300 by rotating shunt end cap 1500
so that conductor 1510 contacts conductors 910-912 when positioned
over the exposed conductors.
Reader end cap 1550 may be positioned over the other exposed end of
pad 1300 so that conductors 1570, 1580, and 1590 electrically
couples to conductors 910, 912, and 914 respectively. Conductors
1570, 1580, and 1590 physically contacts conductors 910, 912, and
914 respectively to establish electrical contact. Surface 1560 of
reader end cap 1550 contacts surface 1410 of pad 1300. Surface 1560
may include an adhesive to retain conductors 1570, 1580, and 1590
of reader end cap 1550 mechanically and electrically coupled to
conductors 910, 912, and 914 respectively of pad 1300. Reader end
cap 1550 may have conductors 1570, 1580, and 1590 on both sides of
reader end cap 1550 so that conductors 1570, 1580, and 1590 may
couple to conductors 910, 912, and 914 respectively on either end
of pad 1300.
Reader end cap 1550 may include conductive tabs 1573, 1582, and
1592 that electrically couple to conductors 1570, 1580, and 1590
respectively. Reader 120 may electrically and mechanically to tabs
1572, 1582, and 1592 in any conventional manner so that reader 120
electrically couples to conductors 910, 912, and 914. Tabs 1572,
1582, and 1592 may be omitted when conductors 1570, 1580, and 1590
are exposed on both sides of reader end cap 1550 because reader 120
may electrically and mechanically couple to the exposed conductors
of reader end cap 1550 to establish an electrical coupling with
conductors 910, 912, and 914.
Lengths of pad 1300 may be coupled together using fittings to form
a sensor of various shapes and/or sizes. Fittings may couple two
lengths of sensor together in line or at an angle. Lengths of
sensor and fittings may be used as a modular system to form sensors
of a variety of shapes and/or size. A modular system may include
shunt and reader end caps used at the ends of the aggregate system
as discussed above. A modular system may further include a pad,
such as pad 1610, 1612, and 1614 that have a fixed length that may
also be coupled together using fittings. Pads 1610-1614 may include
cover 1672. Substrate 1670 may be rigid.
For example, modular sensor system 1600 includes sensors 1610-1614
and 90-degree fittings (e.g., couplings) 1620. Sensors 1610-1614
each have a length of length 1650. Any number of sensors may be
coupled together using fittings that permit any orientation between
the sensors to form a system of any size and/or shape.
The end portions of sensors 1610-1614 are exposed so that
conductors 910-914 are accessible for mechanical and electrical
coupling. Fittings couple to end portions of sensors 1610-1614 to
couple conductors 910, 912, and 914 of one sensor to conductors
910, 912, and 914 respectively of another sensor.
Fittings may be of any angle (e.g., 33, 45, 90, 180 degrees). The
conductors of the fittings may include conductors positioned to
match (e.g., line-up with) the spacing (e.g., positions) of
conductors 910, 912, and 914 of the sensors 1610-1614. A surface of
a fitting may include an adhesive for coupling to sensors 1610-1614
for retaining mechanical and electrical coupling of the fitting to
sensors 1610-1614.
For example, fitting 1620 is an implementation of a 90 degree
fitting. Fitting 1620 is positioned with respect to the exposed end
portions of two lengths of sensor (e.g., 1610-1614) so that
conductor 1770, 1780, and 1790 of fitting 1620 contacts and
electrically couples to conductors 914, 912, and 910 respectively
of the exposed ends.
End caps for shunting and for a reader, as discussed above, may be
coupled to the end portions of an assembled modular system for
coupling a reader and detecting moisture.
Modular system 1600 may be used in an implementation of a sensor
for detecting a leak in a roof of a building as disclosed in U.S.
provisional patent application No. 62/081,662 ("'662") entitled
Methods and Apparatus for Leak Detection in a Roof, filed Nov. 19,
2014 naming Brian C. Woodbury as the first named inventor. The '662
application is incorporated herein by reference. The information
disclosed in the '662 application may be used for any purpose in
this application. Further, the disclosure of the '622 may
considered in terms of replacing the three wire sensors of the '662
application with the sensors disclosed in pads 810, 1300, and/or
1610.
The foregoing description discusses preferred embodiments of the
present invention, which may be changed or modified without
departing from the scope of the present invention as defined in the
claims. Examples listed in parentheses may be used in the
alternative or in any practical combination. As used in the
specification and claims, the words `comprising`, `including`, and
`having` introduce an open ended statement of component structures
and/or functions. In the specification and claims, the words `a`
and `an` are used as indefinite articles meaning `one or more`.
When a descriptive phrase includes a series of nouns and/or
adjectives, each successive word is intended to modify the entire
combination of words preceding it. For example, a black dog house
is intended to mean a house for a black dog. While for the sake of
clarity of description, several specific embodiments of the
invention have been described, the scope of the invention is
intended to be measured by the claims as set forth below. In the
claims, the term "provided" is used to definitively identify an
object that not a claimed element of the invention but an object
that performs the function of a workpiece that cooperates with the
claimed invention. For example, in the claim "an apparatus for
aiming a provided barrel, the apparatus comprising: a housing, the
barrel positioned in the housing", the barrel is not a claimed
element of the apparatus, but an object that cooperates with the
"housing" of the "apparatus" by being positioned in the
"housing".
* * * * *